The invention relates to a receiving system for receiving a digital broadcast signal in which, for example, video data and audio data are broadcasted by a transport stream of an MPEG (Moving Picture Experts Group) 2 system and transmitting the transport stream to digital signal processing equipment through an interface of IEEE (Institute of Electrical Electronic Engineers) 1394. The invention also relates to a receiving apparatus for a digital broadcasting which is used for such a system.
In recent years, IEEE 1394 has gained popularity as an interface to transfer video data and audio data between digital video equipment and digital audio equipment at a high speed. IEEE 1394 supports an isochronous transfer mode and an asynchronous transfer mode. A delay time of a data transfer is guaranteed in the isochronous transfer mode. The isochronous transfer mode is suitable to transfer a time-sequential data stream such as video data or audio data at a high speed. The asynchronous transfer mode is suitable to transfer ordinary data such as various commands or the like.
In recent years, digital satellite broadcasting has also gained in popularity. In the digital satellite broadcasting, a digital video signal and an audio signal are compressed by an MPEG2 system, multiplexed into a packet stream, and transmitted. A digital satellite broadcast signal is typically received by an IRD (Integrated Receiver Decoder) which is connected to a television receiver. A desired program signal is selected by the IRD and a video signal and an audio signal are decoded. An output of the IRD may then be supplied to the TV receiver.
A method of providing an IEEE 1394 interface on an IRD to receive such a digital satellite broadcast signal has been proposed. When an IEEE 1394 interface is provided for an IRD, the IRD is connected to a digital video recording and reproducing apparatus or an MD recording and reproducing apparatus through the IEEE 1394 interface and a receiving system so that the digital satellite broadcast signal can be constructed.
In accordance with the IEEE 1394 standard, when data is transferred, an ID number of a node is allocated and a partner is designated by the ID number of the node. The node ID numbers which can be allocated to a bus of IEEE 1394 are “0” to “63.” The last node number among them is used for broadcasting. Now, assuming that broadcast is not used, then up to 63 equipment units can be connected to one bus.
In case of constructing a receiving system for digital satellite broadcasting by using an IRD having an IEEE 1394 interface as mentioned above, a method whereby the ID numbers of the nodes are allocated for up to 63 equipment units in accordance with the IEEE 1394 standard to thereby enable data to be transmitted to such equipment is considered.
Generally, in the receiving system for the digital satellite broadcasting, however, it is hard to consider a situation where 63 equipment units are connected to the IEEE 1394 bus and used. Thus, it is generally accepted that the number of equipment that will be connected to the IEEE 1394 bus is equal to or less than 5. In addition, if up to 63 equipment units can be connected in accordance with the IEEE 1394 standard, efficiency deteriorates. For example, when recording is desired, equipment to record is selected. In this instance, if the number of equipment that is be connected is larger than the number of equipment units actually used, a number of equipment units are arranged on a selection display picture plane and it is difficult to select the desired equipment.
A GUI picture plane showing operations and control states of a plurality of equipment units connected to a bus of IEEE 1394 is disclosed in U.S. Pat. Nos. 5,793,366 and 5,883,621. By observing the GUI picture plane, the user can visually recognize which equipment is presently connected to the IEEE 1394 bus, from which equipment and to which equipment data is transmitted, and further, to which equipment the recording is performed. According to those patents, however, the IRD can recognize only the equipment connected to the IEEE 1394 bus and, once such equipment is disconnected, the equipment can no longer be recognized. Therefore, each time equipment is connected to the IEEE 1394 bus, such equipment has to be set and recognized on the IEEE 1394 bus.